client/src/variants/Pacifist1.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class Pacifist1Rules extends ChessRules {
   4   static get PawnSpecs() {
   5     return Object.assign(
   6       {},
   7       ChessRules.PawnSpecs,
   8       { canCapture: false }
   9     );
  10   }
  11
  12   static get HasEnpassant() {
  13     return false;
  14   }
  15
  16   static IsGoodPosition(position) {
  17     if (position.length == 0) return false;
  18     const rows = position.split("/");
  19     if (rows.length != V.size.x) return false;
  20     let kingsCount = 0;
  21     for (let row of rows) {
  22       let sumElts = 0;
  23       for (let i = 0; i < row.length; i++) {
  24         if (['K','k'].includes(row[i])) kingsCount++;
  25         if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
  26         else {
  27           const num = parseInt(row[i], 10);
  28           if (isNaN(num)) return false;
  29           sumElts += num;
  30         }
  31       }
  32       if (sumElts != V.size.y) return false;
  33     }
  34     // Both kings should be on board. May be of the same color.
  35     if (kingsCount != 2) return false;
  36     return true;
  37   }
  38
  39   scanKings(fen) {
  40     // Kings may be swapped, so they are not tracked (no kingPos)
  41     this.INIT_COL_KING = { w: -1, b: -1 };
  42     const fenRows = V.ParseFen(fen).position.split("/");
  43     const startRow = { 'w': V.size.x - 1, 'b': 0 };
  44     for (let i = 0; i < fenRows.length; i++) {
  45       let k = 0; //column index on board
  46       for (let j = 0; j < fenRows[i].length; j++) {
  47         switch (fenRows[i].charAt(j)) {
  48           case "k":
  49             this.INIT_COL_KING["b"] = k;
  50             break;
  51           case "K":
  52             this.INIT_COL_KING["w"] = k;
  53             break;
  54           default: {
  55             const num = parseInt(fenRows[i].charAt(j), 10);
  56             if (!isNaN(num)) k += num - 1;
  57           }
  58         }
  59         k++;
  60       }
  61     }
  62   }
  63
  64   // Sum white pieces attacking a square, and remove black pieces count.
  65   sumAttacks([x, y]) {
  66     const getSign = (color) => {
  67       return (color == 'w' ? 1 : -1);
  68     };
  69     let res = 0;
  70     // Knights:
  71     V.steps[V.KNIGHT].forEach(s => {
  72       const [i, j] = [x + s[0], y + s[1]];
  73       if (V.OnBoard(i, j) && this.getPiece(i, j) == V.KNIGHT)
  74         res += getSign(this.getColor(i, j));
  75     });
  76     // Kings:
  77     V.steps[V.ROOK].concat(V.steps[V.BISHOP]).forEach(s => {
  78       const [i, j] = [x + s[0], y + s[1]];
  79       if (V.OnBoard(i, j) && this.getPiece(i, j) == V.KING)
  80         res += getSign(this.getColor(i, j));
  81     });
  82     // Pawns:
  83     for (let c of ['w', 'b']) {
  84       for (let shift of [-1, 1]) {
  85         const sign = getSign(c);
  86         const [i, j] = [x + sign, y + shift];
  87         if (
  88           V.OnBoard(i, j) &&
  89           this.getPiece(i, j) == V.PAWN &&
  90           this.getColor(i, j) == c
  91         ) {
  92           res += sign;
  93         }
  94       }
  95     }
  96     // Other pieces (sliders):
  97     V.steps[V.ROOK].concat(V.steps[V.BISHOP]).forEach(s => {
  98       let [i, j] = [x + s[0], y + s[1]];
  99       let compatible = [V.QUEEN];
 100       compatible.push(s[0] == 0 || s[1] == 0 ? V.ROOK : V.BISHOP);
 101       let firstCol = undefined;
 102       while (V.OnBoard(i, j)) {
 103         if (this.board[i][j] != V.EMPTY) {
 104           if (!(compatible.includes(this.getPiece(i, j)))) break;
 105           const colIJ = this.getColor(i, j);
 106           if (!firstCol) firstCol = colIJ;
 107           if (colIJ == firstCol) res += getSign(colIJ);
 108           else break;
 109         }
 110         i += s[0];
 111         j += s[1];
 112       }
 113     });
 114     return res;
 115   }
 116
 117   getPotentialMovesFrom([x, y]) {
 118     let moves = super.getPotentialMovesFrom([x, y]);
 119     const color = this.turn;
 120     const oppCol = V.GetOppCol(color);
 121     if (this.getPiece(x, y) == V.PAWN) {
 122       // Pawns cannot move 2 squares if the intermediate is overly persuaded
 123       moves = moves.filter(m => {
 124         if (Math.abs(m.end.x - m.start.x) == 2) {
 125           const [i, j] = [(m.start.x + m.end.x) / 2, y];
 126           const persuasion = this.sumAttacks([i, j]);
 127           return (
 128             color == 'w' && persuasion >= 0 ||
 129             color == 'b' && persuasion <= 0
 130           );
 131         }
 132         return true;
 133       });
 134     }
 135     // Potentially flipped (opp) pieces
 136     let targets = [];
 137     for (let i=0; i<8; i++) {
 138       for (let j=0; j<8; j++) {
 139         if (this.board[i][j] != V.EMPTY && this.getColor(i, j) == oppCol)
 140           targets.push([i, j]);
 141       }
 142     }
 143     moves.forEach(m => {
 144       // Start persuading other pieces: loop until nothing changes
 145       V.PlayOnBoard(this.board, m);
 146       while (true) {
 147         let persuaded = [];
 148         targets.forEach(t => {
 149           if (this.getColor(t[0], t[1]) == oppCol) {
 150             const sqAttacks = this.sumAttacks([t[0], t[1]]);
 151             if (
 152               (oppCol == 'w' && sqAttacks < 0) ||
 153               (oppCol == 'b' && sqAttacks > 0)
 154             ) {
 155               persuaded.push(t);
 156             }
 157           }
 158         });
 159         if (persuaded.length == 0) break;
 160         persuaded.forEach(p => {
 161           this.board[p[0]][p[1]] = color + this.getPiece(p[0], p[1]);
 162         });
 163       }
 164       V.UndoOnBoard(this.board, m);
 165       // Reset pieces colors + adjust move (flipped pieces)
 166       targets.forEach(t => {
 167         if (this.getColor(t[0], t[1]) == color) {
 168           const piece = this.getPiece(t[0], t[1]);
 169           m.appear.push({ x: t[0], y: t[1], c: color, p: piece });
 170           m.vanish.push({ x: t[0], y: t[1], c: oppCol, p: piece });
 171           this.board[t[0]][t[1]] = oppCol + piece;
 172         }
 173       });
 174     });
 175     return moves;
 176   }
 177
 178   getSlideNJumpMoves([x, y], steps, oneStep) {
 179     let moves = [];
 180     outerLoop: for (let loop = 0; loop < steps.length; loop++) {
 181       const step = steps[loop];
 182       let i = x + step[0];
 183       let j = y + step[1];
 184       while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
 185         moves.push(this.getBasicMove([x, y], [i, j]));
 186         if (oneStep) continue outerLoop;
 187         i += step[0];
 188         j += step[1];
 189       }
 190       // No captures
 191     }
 192     return moves;
 193   }
 194
 195   underCheck(color) {
 196     // Find the king(s) and determine if it (both) is persuaded.
 197     // If yes, "under check"
 198     let kingPos = [];
 199     for (let i=0; i<8; i++) {
 200       for (let j=0; j<8; j++) {
 201         if (this.getPiece(i, j) == V.KING && this.getColor(i, j) == color)
 202           kingPos.push([i, j]);
 203       }
 204     }
 205     return kingPos.every(kp => {
 206       const persuasion = this.sumAttacks(kp);
 207       return (
 208         (color == 'w' && persuasion < 0) ||
 209         (color == 'b' && persuasion > 0)
 210       );
 211     });
 212   }
 213
 214   filterValid(moves) {
 215     const fmoves = super.filterValid(moves);
 216     const color = this.turn;
 217     // If the king isn't here, only moves persuading a king are valid
 218     const kingHere = this.board.some(b =>
 219       b.some(cell => cell[0] == color && cell[1] == V.KING)
 220     );
 221     if (!kingHere) {
 222       return (
 223         fmoves.filter(m => m.appear.some(a => a.c == color && a.p == V.KING))
 224       );
 225     }
 226     return fmoves;
 227   }
 228
 229   getCheckSquares() {
 230     // There are not really "checks": just color change
 231     return [];
 232   }
 233
 234   getCurrentScore() {
 235     const color = this.turn;
 236     // TODO: if no king of turn color, and no move to get one, then it's lost
 237     // otherwise 1/2 if no moves, or "*"
 238     const kingHere = this.board.some(b =>
 239       b.some(cell => cell[0] == color && cell[1] == V.KING)
 240     );
 241     if (kingHere) {
 242       if (this.atLeastOneMove()) return "*";
 243       return "1/2";
 244     }
 245     // No king was found: try to convert one
 246     const moves = this.getAllValidMoves();
 247     return (
 248       moves.some(m => m.appear.some(a => a.c == color && a.p == V.KING))
 249         ? "*"
 250         : (color == 'w' ? "0-1" : "1-0")
 251     );
 252   }
 253
 254   postPlay(move) {
 255     this.updateCastleFlags(move, move.vanish[0].p);
 256   }
 257
 258   postUndo() {}
 259
 260   static get SEARCH_DEPTH() {
 261     return 1;
 262   }
 263 };